PDIUSBD11 Datasheet, PDF (17/20 Pages) NXP Semiconductors – USB device with serial interface

Philips Semiconductors
USB device with serial interface
Product specification
PDIUSBD11
SOLDERING
Introduction
This text gives a very brief insight to a complex technology. A more
in-depth account of soldering ICs can be found in our “Data
Handbook IC26; Integrated Circuit Packages” (document order
number 9398 652 90011).
There is no soldering method that is ideal for all IC packages. Wave
soldering is often preferred when through-hole and surface mount
components are mixed on one printed circuit board. However, wave
soldering is not always suitable for surface mount ICs, or for
printed-circuit boards with high population densities. In these
situations, reflow soldering is often used.
Through-hole mount packages
SOLDERING BY DIPPING OR BY SOLDER WAVE
The maximum permissible temperature of the solder is 260°C;
solder at this temperature must not be in contact with the joints for
more than 5 seconds. The total contact time of successive solder
waves must not exceed 5 seconds.
The device may be mounted up to the seating plane, but the
temperature of the plastic body must not exceed the specified
maximum storage temperature (T_stg(max)). If the printed-circuit board
has been pre-heated, forced cooling may be necessary immediately
after soldering to keep the temperature within the permissible limit.
MANUAL SOLDERING
Apply the soldering iron (24 V or less) to the lead(s) of the package,
either below the seating plane or not more than 2 mm above it. If the
temperature of the soldering iron bit is less than 300°C, it may
remain in contact for up to 10 seconds. If the bit temperature is
between 300 and 400°C, contact may be made for up to 5 seconds.
Surface mount packages
REFLOW SOLDERING
Reflow soldering requires solder paste (a suspension of fine solder
particles, flux and binding agent) to be applied to the printed-circuit
board by screen printing, stencilling or pressure-syringe dispensing
before package placement.
Several methods exist for reflowing; for example, infrared/convection
heating in a conveyor-type oven. Throughput times (preheating,
soldering and cooling) vary between 100 and 200 seconds,
depending on heating method.
Typical reflow peak temperatures range from 215 250°C. The
top-surface temperature of the packages should preferably be kept
below 230°C.
WAVE SOLDERING
Conventional single-wave soldering is not recommended for surface
mount devices (SMDs) or printed-circuit boards with a high
component density, as solder bridging and non-wetting can present
major problems.
To overcome these problems, the double-wave soldering method
was specifically developed.
If wave soldering is used, the following conditions must be observed
for optimal results:
• Use a double-wave soldering method comprising a turbulent wave
with high upward pressure followed by a smooth laminar wave.
• For packages with leads on two sides and a pitch (e):
– larger than or equal to 1.27 mm, the footprint longitudinal axis
is preferred to be parallel to the transport direction of the
printed-circuit board;
– smaller than 1.27 mm, the footprint longitudinal axis must be
parallel to the transport direction of the printed-circuit board.
The footprint must incorporate solder thieves at the downstream
end.
• For packages with leads on four sides, the footprint must be
placed at a 45° angle to the transport direction of the
printed-circuit board. The footprint must incorporate solder thieves
downstream and at the side corners.
During placement, and before soldering, the package must be fixed
with a droplet of adhesive. The adhesive can be applied by screen
printing, pin transfer or syringe dispensing. The package can be
soldered after the adhesive has cured.
Typical dwell time is 4 seconds at 250°C. A mildly-activated flux will
eliminate the need for removal of corrosive residues in most
applications.
MANUAL SOLDERING
Fix the component by first soldering two diagonally-opposite end
leads. Use a low-voltage (24 V or less) soldering iron applied to the
flat part of the lead. Contact time must be limited to 10 seconds at
up to 300°C.
When using a dedicated tool, all other leads can be soldered in one
operation within 2 to 5 seconds between 270 and 320°C.
1999 Jul 22
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